A Primer on Proxies

Traffic proxying is a valuable privacy tool that encapsulates one flow of data inside another, helping establish boundaries on the internet. MASQUE is a collaboration effort to design efficient proxy protocols based on IETF standards. Forward proxying involves a client establishing an end-to-end tunnel to a target server via a proxy server. TCP provides a reliable byte stream for applications like HTTP and TLS, while various proxy protocols are used for proxying TCP end-to-end, including SOCKS, Transparent TCP proxies, Layer 4 proxies, and HTTP CONNECT. The IETF chose to focus on using HTTP as a substrate via the CONNECT method, which supports different versions of HTTP like HTTP/1.1, HTTP/2, and HTTP/3. QUIC is a new secure and multiplexed transport protocol that provides reliable and ordered streams for applications like HTTP/3. Moving forward, the MASQUE Working Group aims to standardize technologies enabling proxying for datagram-based protocols like UDP and IP.